Electric power generating device

ABSTRACT

There is provided an electric power generating device which includes a generator which is constituted by an interior permanent magnet (IPM) synchronous generator, and is connected to a steam turbine without interposition of a reduction gear, cooling means which flows a liquid coolant used to cool the generator, and a frequency converter which converts an electric power generated by the generator into an electric power at a commercial frequency, and outputs the converted electric power, the cooling means includes a circulation passage to which a tank which is used to store the liquid coolant (oil), a cooler which cools the liquid coolant, and a pump which pressure-feeds the liquid coolant are connected, and through which the liquid coolant circulates, and this configuration enables the generator to operate at a high rotational speed, thereby efficiently utilizing the steam energy.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power generating device which drivesa generator by means of a driving device driven by steam.

2. Description of the Prior Art

In order to interconnect a power generating facility to a system, it isnecessary to set the frequency of a generated electric power to acommercial frequency (50 Hz or 60 Hz). For this purpose, when thecommercial frequency is 60 Hz, the rotational speed of a generator isset to 3600 rpm.

If a turbine which serves as a driving source of a generator is a gasturbine, the drive torque thereof is determined by the quantity of afuel gas (or air) supplied thereto, and if the turbine is a steamturbine, the drive torque thereof is determined by the quantity of steamsupplied thereto. The drive torque and the load torque of the generatorthen determine the rotational speed of the generator. However, even ifthe drive torque of the turbine is sufficiently large, since it isnecessary to set the rotational speed of the generator to 3600 rpm asdescribed above, adjusting means which adjusts the amount of the fuelgas or the steam is provided upstream of the turbine, and a reductiongear is provided on a drive shaft of the turbine at the same time.

For example, Japanese Patent Laid-Open No. 2000-1705548 discloses aconfiguration including a fuel flow rate control valve 120 which adjuststhe quantity of a supplied fuel and a reduction gear 122 which reduces aturbine rotational speed as shown in FIG. 3. Namely, air compressed by acompressor 124 is supplied as air for combustion to a combustor 126, andthe fuel is also supplied to the combustor 126 via the fuel flow ratecontrol valve 120. There is provided such a configuration that a burntgas from the combustor 126 is fed to a turbine 128, and rotationallydrives the turbine 128, and the rotational speed is reduced by thereduction gear 122 provided on a drive shaft of the turbine 128, therebydriving a generator 130.

On the other hand, Japanese Patent Laid-Open No. 2002-84795 disclosessuch a configuration that, in an electric power generating device whichuses a gas turbine engine 140 as a driving source of a generator 142, anelectric power at a frequency higher than the commercial frequency isgenerated, and the electric power at the high frequency is convertedinto an electric power at the commercial frequency by a power converter144, as shown in FIG. 4. Namely, in this power generating device, thegenerator 142 is constituted by a generator which withstands a highrotational speed, the generator 142 is directly coupled to the gasturbine 140, and the gas turbine 140 is driven at a rotational speed oftens to hundreds of thousand rpm to generate an electric power at a highfrequency of approximately 1 to 3 kHz. Then, the electric power at thehigh frequency is once converted into a DC power by a rectifying circuit146, and is further converted into an AC output in synchronous with thecommercial frequency by an inverter 148 for interconnection to thesystem.

However, the above conventional power generating devices have thefollowing problems. Namely, the configuration, which adjusts thesupplied fuel quantity by means of the fuel flow rate control valve inorder to restrict the rotational speed of the generator as disclosed inJapanese Patent Laid-Open No. 2000-170548, poses such a problem that thequantity of the fuel gas fed to the turbine is restricted or the steamis discharged wastefully in some cases, resulting in insufficient use ofthe energy of the fuel gas or the steam. Moreover, since theconfiguration according to this publication has the reduction gear 122to reduce the turbine rotational speed, it is impossible to avoid amechanical loss caused by the reduction gear 122. Moreover, theemployment of the reduction gear 122 poses such a problem that amaintenance thereof requires labors.

On the other hand, according to Japanese Patent Laid-Open No.2002-84795, since the generator 142 can be operated at the highrotational speed, the fuel gas can be sufficiently utilized, and,moreover, since the generator 142 is directly connected to the gasturbine engine 140, this configuration prevents a mechanical loss frombeing generated therebetween. However, since the gas turbine engine 140is configured so as to provide the drive at the high speed of tens tohundreds of thousand rpm, and moreover the gas turbine engine 140 isdirectly connected to the generator 142, there poses a problem of heatgenerated by the generator 142, resulting in a incapability of acontinuous operation at the high rotational speed.

SUMMARY OF THE INVENTION

The present invention is devised in view of the foregoing problems, andhas an objective to efficiently utilize the steam energy so that agenerator can continuously operate at a high rotational speed.

To attain the above objective, the present invention provides anelectric power generating device including a driving device which isdriven by steam, a permanent magnet synchronous generator which isdriven by the driving device to generate an electric power, thepermanent magnet synchronous generator being connected to the drivingdevice without a reduction gear being interposed, cooling means whichcirculates a liquid coolant which cools the permanent magnet synchronousgenerator, and a frequency converter which converts the electric powergenerated by the permanent magnet synchronous generator to an electricpower at a commercial frequency.

According to the present invention, since the electric power generatedby the generator is converted by the frequency converter into theelectric power at the commercial frequency, it is possible to avoid therestriction on the rotational speed of the generator in order togenerate an electric power at a predetermined frequency. As a result,the driving device can be driven at the rotational speed according tothe flow rate of the steam supplied to the electric power generatingdevice, resulting in utilizing the steam without a waste. Moreover,since the permanent magnet synchronous generator is used as a generator,it is possible to carry out efficient power generation in a high speedrotation range, and since the driving device and the generator aredirectly connected without interposition of a reduction gear, themechanical loss is small therebetween, thereby also contributing to anincrease of the efficiency of the electric power generation. Moreover,since the liquid coolant used to cool the permanent magnet synchronousgenerator is circulated in addition to the employment of the permanentmagnet synchronous generator as the generator, it is possible toefficiently restrain the permanent magnet synchronous generator fromgenerating heat. As a result, the permanent magnet synchronous generatorcan continuously operate at the high rotational speed.

With this configuration, a steam turbine or a screw expander may be usedas the driving device.

When the permanent magnet synchronous generator is an interior permanentmagnet synchronous generator, it is possible to further restrain thequantity of the heat generated by the generator.

The cooling means preferably comprises a circulation passage to which atank which stores the liquid coolant, a cooler which cools the liquidcoolant, and a pump which pressure-feeds the liquid coolant areconnected, thereby circulating the liquid coolant.

With this configuration, since the liquid coolant is circulated whilethe liquid coolant is being cooled, it is possible to cool the permanentmagnet synchronous generator without consuming a large amount of theliquid coolant. Moreover, it is possible to adjust the circulatingquantity of the liquid coolant by means of the drive of the pump, andthe permanent magnet synchronous generator can thus be properly cooled.

With this configuration, the circulation passage preferably communicateswith a cooling passage provided on a body section of a casing of thepermanent magnet synchronous generator. As a result, since the permanentmagnet synchronous generator is cooled by flowing the liquid coolantthrough the body section of the casing of the permanent magnetsynchronous generator, the permanent magnet synchronous generator can beefficiently cooled.

Then, the cooling passage may be provided through the body section ofthe casing in peripheral and axial directions. With this configuration,it is possible to deliver the liquid coolant across the inside of thebody section of the casing, and thus to evenly cool the permanent magnetsynchronous generator.

Moreover, preferably, the electric power generating device according tothe present invention further includes a main pipe which leads steamgenerated by steam generating means to a steam utilizing facility, aninlet pipe which is connected to an inlet side of the driving device,the inlet pipe being connected to the main pipe, and an outlet pipewhich is connected to an outlet side of the driving device, the outletpipe being connected to the main pipe. With this configuration, thesteam flowing through the main pipe flows into the inlet pipe, is fed tothe driving device, is discharged from the driving device, and returnsto the main pipe through the outlet pipe.

With this configuration, since the electric power can be generated byutilizing the steam before the steam is fed to the steam utilizingfacility, it is possible to increase the efficiency of the utilizationof the steam generated by the steam generating means. Particularly, thisconfiguration is efficient for a case where connections are made to themain pipe connected to a steam utilizing facility which uses steam at alow pressure.

As described above, according to the present invention, since thedriving device can be driven at the rotational speed according to theflow rate of the steam supplied to the electric power generating device,and it is also possible to restrain the heat generation of the permanentmagnet synchronous generator, the operation of the permanent magnetsynchronous generator can be maintained at a high rotational speed. Thesteam energy can thus be efficiently utilized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing an overall configuration of anelectric power generating device according to an embodiment of thepresent invention;

FIG. 2 is a cross sectional view showing a generator and a liquidcoolant tank provided for the electric power generating device;

FIG. 3 is a view showing a configuration of a conventional powergenerating device; and

FIG. 4 is a view showing a configuration of a conventional powergenerating device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A detailed description will now be given of an embodiment of the presentinvention with reference to drawings.

FIG. 1 shows an embodiment of an electric power generating device 20according to the present invention. As FIG. 1 shows, the electric powergenerating device 20 generates an electric power by means of an energyof steam generated by steam generating means 10, and is used by a steamutilizing facility 12. A specific description will now be given.

The steam generating means 10 and the steam utilizing facility 12 areconnected with each other by means of a main pipe 14 through which thesteam flows. On the main pipe 14 is provided a pressure reducing valve16.

The steam generating means 10 include multiple boilers 10 a connected inparallel to the main pipe 14. As these respective boilers 10 a are usedboilers which generate a quantity of steam of approximately 2 ton/hour,for example, and the boilers 10 a are respectively constituted by asmall once-through boiler.

The steam utilizing facility 12 is a facility such as water heater, aspace heater, a bath facility, a drying tumbler, a washing facility, akitchen machine, or a sterilizer, which use steam at approximately 150to 200° C., for example.

The electric power generating device 20 according to the presentembodiment includes a steam turbine 22, a generator 24, a frequencyconverter 26, a controller 28, and cooling means 30, and are stored in acasing 32. It should be noted a ventilation fan 34 is provided for thecasing 32.

The steam turbine 22 is constituted by an axial flow turbine, forexample. The steam turbine 22 is selected so that the maximum rotationalspeed attained by the maximum supplied quantity of the subject steamfalls within a permissible range of the rotational speed.

The steam turbine 22 is provided with an inlet pipe 36 which isconnected to an inlet side of the steam turbine 22, and an outlet pipe38 which is connected to an outlet side of the steam turbine 22. Theinlet pipe 36 is connected to the upstream side of the pressure reducingvalve 16 of the main pile 14, and the outlet pipe 38 is connected to thedownstream side of the pressure reducing valve 16 of the main pipe 14.With this configuration, at least a part of the steam generated by thesteam generating means 10 is fed to the steam turbine 22, and steamdischarged from the steam turbine 22 is returned to the main pipe 14.

On the inlet pipe 36, an open/close valve 40, a drain separator 42, aflow regulating valve 44, and an emergency shutoff valve 46 aresequentially provided from the upstream side. The open/close valve 40 isprovided close to a portion connected to the main pipe 14. The drainseparator 42 is used to separate a drain from the steam flowing throughthe inlet pipe 36. The flow regulating valve 44 is used to adjust theflow rate of the steam flowing through the inlet pipe 36, and iscontrolled to open/close by the controller 28. The emergency shutoffvalve 46 is used to completely shut off the inlet pipe 36, and can becontrolled by the controller 28.

An open/close valve 50 is provided to the outlet pipe 38 close to aportion connected to the main pipe 14. This open/close valve 50 and theopen/close valve 40 on the inlet pipe 36 constitute switching meanswhich switches whether the steam flowing through the main pipe 14 is fedto the inlet pipe 36 or not. Namely, when the steam generated by thesteam generating means 10 is directly fed to the steam utilizingfacility 12, these open/close valves 40 and 50 are closed, and if theelectric power generation is carried out using the steam, theseopen/close valves 40 and 50 are opened. It should be noted that theopen/close valves 40 and 50 can be constituted either by an open/closevalve which can be switched to two states: fully closed and fully openstates, or an open/close valve whose opening is adjustable. Moreover, asthe switching means, three-way valves may be provided in place of theopen/close valves 40 and 50. In this case, the three-way valves areprovided at the portion connecting the main pipe 14 and the inlet pipe36 with each other, and at the portion connecting the main pipe 14 andthe outlet pipe 38 with each other.

On the inlet pipe 36 is provided a pressure sensor 52 which detects thepressure of the steam fed to the steam turbine 22. On the outlet pipe 38is provided a pressure sensor 56 which detects the pressure of the steamdischarged from the steam turbine 22.

A rotation shaft 60 of the generator 24 is coupled to a drive shaft 64of the steam turbine 22 via a coupling 62. Namely, the rotation shaft 60of the generator 24 is connected to the drive shaft 64 of the steamturbine 22 without interposition of a reduction gear. As a result, theoperational rotational speed of the generator 24 is equal to therotational speed of the steam turbine 22.

The electric power generated by the generator 24 is fed to the frequencyconverter 26. The frequency converter 26 is used to convert thefrequency of the electric power generated by the generator 24, andconverts an electric power at 10 to 100 Hz to an electric power at thecommercial frequency of 60 Hz, for example. A pulse generator 66 isprovided on the rotation shaft 60 of the generator 24, and the frequencyconverter 26 provides switching control of internal elements accordingto an output value of the pulse generator 66, thereby converting the ACto a DC. Then, the frequency generator 26 converts the electric power ofthis DC into the electric power at the commercial frequency. Theelectric power output from the frequency converter 26 is interconnectedwith a system 70 via a transformer 68.

The controller 28 determines a proper rotational speed based on thedetection signals from the pressure sensors 52 and 56. Namely, therelationship between the steam flow rate and the proper rotational speedis approximated as a first order proportional relationship, and, thus,the controller 28 determines the flow rate of the steam supplied to thesteam turbine 22 based on the detection values from the pressure sensors52 and 56 respectively provided upstream and downstream of the steamturbine 22, and then determines the proper rotational speed based onthis steam flow rate. The frequency converter 26 outputs a rotationalspeed control signal to the generator 24 based on the proper rotationalspeed determined by the controller 28. As a result, the generator 24 isoperated at the proper rotational speed based on the steam flow rate.

The cooling means 30 is used to cool the generator 24, and includes acirculation passage 72 through which the liquid coolant circulates. Onthe circulation passage 72 are provided a liquid coolant tank 74, a pump75, and a cooler 76. The liquid coolant tank 74 is used to store theliquid coolant. The pump 75 is used to pressure-feed the liquid coolantin the liquid coolant tank 74, and the pump 75 is thus driven so as tocirculate the liquid coolant through the circulation passage 72. Thecooler 76 is used to cool the liquid coolant fed to the generator 24,and is provided with a cooling water passage 76 a used to flow coolingwater, and the cooling water flowing through the cooling water passage76 a cools the liquid coolant. Oil is used as the liquid coolant, forexample.

The generator 24 includes a generator casing 80 having a body section 80a formed approximately into a cylinder, and end wall sections 80 bprovided on both ends of the body section 80 a as shown in FIG. 2, andis disposed on the liquid coolant tank 74 so that the axial direction ofthe body section 80 a is horizontal. Bosses 80 c in a cylindrical shapeprotruding inward are respectively provided on both the end wallsections 80 b of the generator casing 80, and the rotation shaft 60passes through both the boss sections 80 c. Bearings 82 are respectivelyprovided on the boss sections 80 c causing the rotation shaft 60 tofreely rotate.

The rotation shaft 60 is disposed to extend horizontally, extendsoutward from one of the boss sections 80 c (one on the left side in FIG.2), and is coupled to the drive shaft 64 of the steam turbine 22 via thecoupling 62.

On the end wall sections 80 b of the generator casing 80 arerespectively formed oil supply holes 80 d which extend from a top endsection of the generator casing 80 toward the inside of the respectiveboss sections 80 c. Lubricating oil is supplied to the bearings 82through the oil supply holes 80 d. Shaft seal sections 84 arerespectively provided axially outside the bearings 82 in the bosssections 80 c to prevent the lubricating oil for the bearings 82 fromleaking outside. On the other hand, on a bottom section of the generatorcasing 80 are provided communication passages 88 which cause the insideof the generator casing 80 and the top openings 86 of the liquid coolanttank 74 to communicate with each other, and the lubricating oil whichflows out from the inside of the boss sections 80 c into the generatorcasing 80 flows down into the liquid coolant tank 74 through thecommunication passages 88. Namely, the lubricating oil is the same asthe oil used as the liquid coolant. It should be noted that, in place ofthe configuration to form the communication passages 88 in the generatorcasing 80, there may be provided such a configuration that pipes extendoutward from the bottom end section of the generator casing 80 (notshown), and extreme ends of the pipes are respectively connected to theliquid coolant tank 74.

The generator 24 is constituted by an interior permanent magnet (IPM)synchronous generator. Namely, a stator 90 is fixed to the body section80 a of the generator casing 80, and a rotor 91 is provided on an innerperiphery side of the stator 90. Inside the rotor 91 is embedded apermanent magnet (not shown), and the rotor 91 is fixed to the rotationshaft 60. It should be noted that the generator 24 is selected such thatthe maximum rotational speed of the steam turbine 22 falls within thepermissible rotational speed.

A coil 93 is wound on the stator 90, and is connected to an electricequipment port 95. To this electric equipment port 95 are connectedwires connected to the frequency converter 26. On the coil 93 isprovided a temperature sensor, which is not shown, and the temperaturesensor is connected to the electric equipment port 96. To this electricequipment port 96 are connected wires connected to the controller 28.

On the body section 80 a of the generator casing 80 are provided aninlet port 98 and an outlet port 99, and the inlet port 98 and theoutlet port 99 are connected with each other by a cooling passage 100formed in the body section 80 a. The inlet port 98 is provided on oneside of the body section 80 a, and an end of the cooler 76 side in thecirculation passage 72 is connected thereto. On the other hand, theoutlet port 99 is provided on the other side of the body section 80 a,and an end of the liquid coolant tank 74 side in the circulation passage72 is connected thereto.

The cooling passage 100 includes multiple peripheral-direction sections100 a which are disposed at an interval in the axial direction, andextend in the peripheral direction in the body section 80 a, and anaxial-direction section 100 b which extends in the axial direction so asto cause the peripheral-direction sections 100 a to communicate witheach other. Then, the liquid coolant fed through the inlet port 98 flowsthough the peripheral-direction sections 100 a and the axial-directionsection 100 b toward the outlet port 99. As a result, the body section80 a of the generator casing 80 is evenly cooled.

A description will now be given of the operation of the electric powergenerating device 20. The steam generated by driving the respectiveboilers 10 a flows through the main pipe 14, is reduced in pressure bythe pressure reduction valve 16, and is then fed to the steam utilizingfacility 12. Then, when the electric power generation is carried out,the open/close valve 40 on the inlet pipe 36 and the open/close valve 50on the outlet valve 38 are opened, and, consequently, a part of thesteam which has generated by the respective boilers 10 a, and has flownthrough the main tube 14 is diverted to the inlet pipe 36. Even in thiscase, since the steam is still fed to the steam utilizing facility 12,the steam utilizing facility 12 can utilize the steam.

The steam turbine 22 is driven by the steam diverted to the inlet pipe36, which causes the rotation shaft 60 of the generator 24 to rotate,resulting in the generation of the electric power. On this occasion, theflow rate of the steam supplied to the steam turbine 22 is obtained bythe pressure sensors 52 and 56, and the proper rotational speed underthis steam flow rate is obtained by the controller 28. Then, thegenerator 24 is operated at this proper rotational speed. The steamwhich has driven the steam turbine 22 merges into the steam, which hasflown through the main pipe 14, via the outlet pipe 38, and is suppliedto the steam utilizing facility 12. Namely, even if the quantity of thesteam used in the steam utilizing facility 12 reduces, since theopen/close valves 40 and 50 are opened to use the steam for the electricpower generation, it is possible to continuously operate the respectiveboilers 10 a at a state close to the maximum capacity. Therefore, it ispossible to stably drive the respective boilers 10 a, and to increasethe efficiency of the boilers 10 a.

During the operation of the generator 24, the temperature inside thegenerator 24 is detected by the temperature sensor, not shown, and theliquid coolant is circulating through the circulation passage 72.Namely, the drive of the pump 75 causes the liquid coolant in the liquidcoolant tank 74 is fed out, the liquid coolant is cooled at the cooler76 by the cooling water of the cooling water passage 76 a, and thecooled liquid coolant is fed to the generator 24. Then, the liquidcoolant passes through the inlet port 98, and flows through theperipheral-direction sections 100 a and the axial-direction section 100b of the cooling passage 100, thereby evenly cooling the body section 80a of the generator casing 80. As a result, the heat generated by thegenerator 24 is efficiently restrained. Then, the liquid coolant whichhas flown through the cooling passage 100 passes the outlet port 99,flows through the circulation passage 72, and returns to the liquidcoolant tank 74. The liquid coolant continues this circulation.

The electric power generated by the generator 24 is output to thefrequency converter 26 through the electric equipment port 95. Thefrequency of the electric power is 10 to 100 Hz, for example. Then, theelectric power is converted into the electric power at the commercialfrequency by the frequency converter 26, is output, and isinterconnected to the system 70 via the transformer 68.

As described above, according to the present invention, since theelectric power generated by the generator 24 is converted by thefrequency converter 26 into the electric power at the commercialfrequency, it is possible to avoid the restriction on the rotationalspeed of the generator 24 in order to generate an electric power at apredetermined frequency. As a result, the steam turbine 22 can be drivenat the rotational speed according to the flow rate of the steam suppliedto the electric power generating device 20, resulting in utilizing thesteam without a waste. Moreover, since the generator 24 is constitutedby the permanent magnet synchronous generator, it is possible to carryout efficient power generation in a high speed rotation range, and sincethe steam turbine 22 and the generator 24 are directly connected withoutinterposition of a reduction gear, the mechanical loss is smalltherebetween, thereby also contributing to an increase of the efficiencyof the electric power generation. Moreover, since the liquid coolantused to cool the generator 24 is circulated in addition to theemployment of the permanent magnet synchronous generator as thegenerator 24, it is possible to efficiently restrain the generator 24from generating heat. As a result, the generator 24 can continuouslyoperate at the high rotational speed.

Moreover, according to the present embodiment, since the generator 24 isconfigured by the interior permanent magnet synchronous generator, it ispossible to further restrain the generator 24 from generating heat.

Moreover, according to the present embodiment, since the liquid coolantis circulated while the liquid coolant is being cooled, it is possibleto cool the generator 24 without consuming a large amount of the liquidcoolant, and since it is possible to adjust the circulating quantity ofthe liquid coolant by means of the drive of the pump 75, the generator24 can be properly cooled.

Moreover, according to the present embodiment, since the circulationpassage 72 of the liquid coolant communicates with the cooling passage100 provided on the body section 80 a of the generator casing 80, thegenerator 24 can be efficiently cooled. Moreover, since the coolingpassage 100 is configured so as to be provided through the body section80 a of the generator casing 80 in peripheral and axial directions, itis possible to deliver the liquid coolant across the inside of the bodysection 80 a of the generator casing 80, and thus to evenly cool thegenerator 24.

Moreover, since the electric power can be generated by utilizing thesteam before the steam is fed to the steam utilizing facility 12, it ispossible to increase the efficiency of the utilization of the steamgenerated by the boiler 10 a. Particularly, the configuration isefficient for a case where connections are made to the main pipe 14connected to the steam utilizing facility 12 which uses steam at a lowpressure.

Moreover, though, according to the present embodiment, the steam turbine22 is constituted by an axial flow turbine, the steam turbine 22 may beconstituted by a radial turbine instead.

According to the present invention, any fluid machine may be employed asa driving device used to drive the generator as long as the machinegenerates a rotational force from a flow of steam. Examples of such afluid machine include turbine and screw expander. Thus, the steamturbine 22 may be replaced by a screw expander in the embodiment shownin FIG. 1.

1. An electric power generating device comprising: a driving device thatis driven by steam; a permanent magnet synchronous generator that isdriven by said driving device to generate an electric power, saidpermanent magnet synchronous generator being connected to said drivingdevice without a reduction gear being interposed; cooling means thatcirculates a liquid coolant used to cool said permanent magnetsynchronous generator; and a frequency converter that converts theelectric power generated by said permanent magnet synchronous generatorto an electric power at a commercial frequency.
 2. The electric powergenerating device according to claim 1, wherein said driving device is asteam turbine.
 3. The electric power generating device according toclaim 1, wherein said driving device is a screw expander.
 4. Theelectric power generating device according to claim 1, wherein saidpermanent magnet synchronous generator is an interior permanent magnetsynchronous generator.
 5. The electric power generating device accordingto claim 1, wherein said cooling means comprises a circulation passageto which a tank that stores the liquid coolant, a cooler that cools theliquid coolant, and a pump that pressure-feeds the liquid coolant areconnected, thereby circulating the liquid coolant.
 6. The electric powergenerating device according to claim 5, wherein said circulation passagecommunicates with a cooling passage provided on a body section of acasing of said generator.
 7. The electric power generating deviceaccording to claim 6, wherein said cooling passage is provided throughsaid body section of said casing in peripheral and axial directions. 8.The electric power generating device according to claim 1 furthercomprising: a main pipe that leads steam generated by steam generatingmeans to a steam utilizing facility; an inlet pipe that is connected toan inlet side of said driving device, said inlet pipe being connected tosaid main pipe; and an outlet pipe that is connected to an outlet sideof said driving device, said outlet pipe being connected to said mainpipe, wherein the steam flowing through said main pipe flows into saidinlet pipe, is fed to said driving device, is discharged from saiddriving device, and returns to said main pipe through said outlet pipe.